YSI 6 series Manual de usuario descargar pdf (Pagina 12)

4. Always ensure that the submerged parts of the sonde and wipers are clean before beginning any

turbidity calibration. Remove any brush wipers and replace with a clean, standard (no brush)

wiper. Sediment or other contaminants will compromise the standard if not removed prior to

calibration. Make especially sure the optics are clean, no fingerprints!

5. Always start with the zero (0) NTU standard first. Pour the 0 NTU cal standard into the

calibration cup -- pour down the side so you do not aerate the sample. Secure the sonde into the

calibration cup. Verify that there are no air bubbles on the probe face, run the wiper at least once,

and wait out the probe’s sampling period before accepting the first calibration point.

6. Older YSI 6600 calibration cups (~ 7.5″ length) are slightly shorter than the sonde’s sensor

guard. This shorter cup minimizes the use of standards when calibrating the sensors. In

deployments where low turbidity readings are expected, the sonde should be spaced off the

calibration cup 2.5 inches. The sonde will report a slightly negative reading (typically less than

-1.0 NTU) when calibrated with the sonde resting on the calibration cup.

Note: A longer cal cup is available (p/n 116275) which eliminates the need for the two-inch

spacing. The longer calibration cup is now shipped with all new 6600 sondes.

7. Calibrate the second point, typically 126 NTU. Again, wipe the probe at least once before

pressing the enter button.

Note: Never override a calibration error message without understanding the cause of the

problem. Error messages indicate that a problem exists that could result in incorrect field

readings.

Note: For the YSI prepared AMCO-AEPA standards, the value entered during the calibration protocol

is DIFFERENT depending on which YSI turbidity sensor (6026 or 6136) is being calibrated. The part

numbers for the YSI standards and their calibration values are listed by probe below.

YSI Part Number 6026 Value 6136 Value

608000 0 NTU 0 NTU

607200 10.0 NTU 12.7 NTU

607300 100.0 NTU 126.0 NTU

607400 800.0 NTU 1,000.0 NTU

HOW TO PREVENT NEGATIVE FIELD READINGS

When a sonde is deployed in clean/clear water and it reports negative turbidity data, the cause can

usually be traced to the zero calibration. Despite the best practices it is sometimes impossible to clean

the sonde and the calibration equipment to a point where the zero standard is not contaminated by some

small amount. This is especially true when using previously deployed equipment. A brand new (clean)

instrument can contaminate your zero standard to 0.1 NTU in a lab environment. A used instrument can

contaminate a zero standard to almost 1.0 NTU.

If you have experienced negative field readings, then please review the section titled Optimizing

Turbidity Measurements in Low-Turbidity and Fouling Environments for additional calibration

instructions.

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YSI 6 series Manual de usuario Pagina 12